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Let’s face it – you body is a noisy piece of equipment. You hear pops, snaps, cracks, grating, etc coming from your joints regularly. So what is that all about, and is it ok? Or should you be worried about it?

It’s a question we get asked all the time in the clinic: “So my [insert joint] cracks when I [insert movement]. Is that bad???”

Your joints can make noises for a few different reasons, which I’ll cover below. This conversation usually involves two different types of cracking: joints that crack when you just do normal movements, and joints that you forcefully crack (like cracking your neck or knuckles). So I’ll address these separately.

1. My joints crack on their own when I move them

Joints make noise all the time (some people’s more than others). If you’ve had the pleasure of seeing me in the clinic, then you are likely to have heard my wrists or knees crack as I’m working on you. A lot of these cracks/pops/snaps are simply tissue moving or rubbing across other tissue. There are a lot of ligaments, tendons, connective tissue, fascia and other soft tissues in the body; and they need to be able to move around a bit to allow you to move normally. Sometimes this means they will rub or move over something else (like another tendon, or a bony part of your body). When this happens it can make a sound. Kind of like snapping your fingers.

Sometimes, if you have mild swelling, or some wear and tear in the joints (which EVERYONE will get gradually over time) then the joint surfaces aren’t perfectly smooth and shiny. This can mean you don’t have perfectly smooth gliding of the joint surfaces, and this could make some noise. Lots of people will get a very slight grating sound (like sand paper) when they move their neck or their knees for example.

Finally, you can get what we call “cavitation”. This is what happens when you crack your knuckles. This often happens when you force the joint to crack, but can happen with a normal movement. Some people’s necks will ‘crack’ just by stretching their neck over to the side. I’ll cover cavitation in more detail a little later.

Usually, these noises are perfectly normal and harmless. My general rule for joints that crack are:

If it doesn’t hurt when it cracks, and

If the joint doesn’t get really stuck, and you have to force it to crack to “unstick” it (particularly if this hurts)

Then it is fine and nothing to worry about. If you fail either of the above tests, then it could indicate pathology or some damage to the joint, or other tissues that is causing you pain and locking. If that is the case, then you should get us to check it out, just to be sure. Most of the time it’s still nothing to be too worried about.

2. I crack my neck/knuckles/etc all the time. Is that bad?

Cracking your joints on purpose usually causes this ‘cavitation’ phenomenon. Most joints in your body are synovial joints – meaning they contain synovial fluid in a fully enclosed space (enclosed by ligaments and connective tissue). This makes them essentially water tight and have roughly a fixed amount of fluid in them. Cavitation occurs when you quickly stretch the two joint surfaces apart, increasing the space between. Studies have shown that this creates a gas bubble between the joint surfaces – as the space increased, you essentially run out of fluid to fill it up, so a gas bubble forms. This gets dissolved almost instantly. The crack you hear has been shown to occur when the gas bubble forms.

(Note: it used to be thought that the sound occurred when the bubble dissolved again, but a recent MRI study showed that the crack occurred when the bubble was created. It is also thought that breaking the surface tension between the joint surfaces could lead to some of the sound). Watch the video below to see the exact moment a bubble forms when a knuckle is cavitated

You can see the moment when the joint surfaces separate, and a darker area appears between them. This is the gas bubble forming, and when the pop sound would occur.

Forcing a joint to crack (cavitate) stretches the joint quickly, so it can be useful in loosening a joint up that is too stiff. Physiotherapists and chiropractors often use manipulation or adjustment treatments to crack a joint. However there are some potential risks involved.

But firstly – there is a generally accepted myth that cracking your knuckles causes arthritis. This has been definitively proven not to be true. Rates of arthritis are roughly the same for people who do and don’t crack their knuckles. (So your mum was wrong – sorry mum). However this doesn’t mean that it is perfectly safe to go on cracking everything as much as you want.

Repetitively cracking the same joint the same way for a long period of time can lead to hypermobility of that joint (meaning that it starts to become too mobile). While this isn’t always bad, it can lead to loss of joint control, reduced functional strength and potentially some pain. Remember I said cracking your joints loosens them up – well if you have a joint that is too stiff, then this could help. But what if you have a joint that is already moving too much? It could be hypermobile or you could be much stiffer in other areas, so that one joint is taking all the strain. If you crack that joint it could make it more hypermobile (or put it under more strain). This could actually make your problem worse.

When we use a manipulation technique as a treatment, it is a very specific movement in a very specific direction to one specific joint. When people crack their own necks, for example, it can be very uncontrolled as to which joint actually cracks. Usually the joint that cracks is the one that is easiest to crack (i.e. the most mobile) NOT the stiff segment. This often means that habitual neck crackers are actually exacerbating their own problem.

Cavitation also has some effects on your central nervous system, meaning it usually feels very good when you do it (for a few minutes). Anyone reading this who regularly cracks their neck will recognise that when they do it, they often get instant relief from their neck pain/headaches – for about 30 minutes or so (particularly if you’ve been doing it for a long time). Then you keep doing the same things and the pain comes back. So what do you do? You crack you neck again of course. This becomes like an addictive behavior, but over time it can become less effective. Maybe when you crack your neck, it doesn’t take the pain away any more. Or even worse, maybe you’ve done it so much that the joint has become so stretched that you can’t make it crack any more.

Stop doing this!

The best solution (like most addiction) is to go cold turkey if you can. This will often leave you feeling worse in the short term, but once your joints start to settle down and stiffen up a little bit (back to normal) you will find it will feel better. Often people who have to crack their joints end up being too mobile, and having poor control of their joints. Retraining them with strength and muscle control rehabilitation usually is quite effective in improving their symptoms.

Finally, on the subject of cracking your neck. There is a very small but very real chance of damaging some of the arteries in your neck when you crack it (particularly if you do it certain ways). This could lead to stroke, artery rupture or death. This sometimes gets blown up way out of proportion in the media but there are certainly occasions where people have died after having their neck “adjusted” or “manipulated”. The risks are actually very low – any adverse effects are reported to be between 1 in 400,000 manipulations and 1 in 5.8 million manipulations, and death only occurred a handful of times. The statistics we have also only measure people who’ve had a manipulation with a qualified health professional that has been recorded. I’m sure there are many more people who are cracking their own necks (as well as lots of dodgy operators who are cracking joints without any quality training, recording or assessment procedures) which would actually make the real world risks far lower.

To be safe, before we ever use a manipulation technique on someone’s neck, we go through a series of tests to make sure it is safe to do the treatment. If you have no problems with the testing, you should have no problems with the treatment. We also are very careful to treat in specific ways so as to not cause any damage (To be technical we NEVER use end of range gross rotation manipulations). If the ‘health professional’ you are seeing does not test you (or can’t tell you about why or what should be tested) you shouldn’t let them crack your neck!

So is it bad for you?

So to recap:

Joints (and tendons/ligaments) will often make noise during normal movements. If this

Is not painful, and

Does not cause any significant locking

Then it should be fine, and nothing to worry about.

If you are regularly cracking a joint in your body (your knuckles for example) it is unlikely to cause any arthritis or serious joint damage. If you overdo it for a long period of time it could possibly lead to some joint hypermobility, which could cause some weakness and pain potentially. If you are having to crack your spine regularly (particularly your neck) I would recommend that you stop doing it as much as you can. If you are having to crack your joints all the time, it is obviously not fixing your problem, just giving you short term relief (and may actually be making your problem worse). If it is your neck, there is a very small risk that you could do some serious harm. Usually people who are habitually cracking their joints for pain relief actually have a muscle control problem or joint stiffness in a different area that needs addressing, rather than persistent joint cracking.

As a general rule we don’t recommend that you continue to crack your joints for a long period of time, particularly if you have to force it.

If you have any concerns regarding your noisy joints (or if you are a habitual neck cracker looking for a more long term solution) please feel free to contact us. We are always happy to hear from you.

Julian Bowen

Julian is the owner and Principal Physiotherapist at EMC Physiotherapy. He has spent over a decade working exclusively in private physiotherapy practice, and estimates he would have performed over 35,000 individual treatments in that time. He has worked with everyone from Paralympians, elite athletes, WAFL Footballers, the Defence Forces and weekend warriors; to thousands of everyday people with all manner of issues. He is passionate about injury prevention and has a special interest in the treatment of headaches, shoulder issues, hypermobility management and exercise rehabilitation for the prevention and treatment of injuries.